1. Field of the Invention
This invention relates to a system for receiving a remote control signal in an automatic telephone answering device, which is provided with a remote control signal detector including a filter for detecting a remote control signal from a transmission line and message sending means controlled by the detected output from the remote control signal detector to send a message to the transmission line.
2. Description of the Prior Art
A conventional automatic telephone answering device of this kind is a remote-controlled automatic telephone answering and recording set. Since the automatic telephone answering and recording set utilizes a public telephone line, the frequency of the remote control signal is required to be included within the voice band. In the remote-controlled automatic telephone answering and recording set, a remote control signal detector is usually coupled to a line transformer. In this instance, the remote control signal detector is supplied with a remote control signal (a) from a telephone line and a regenerated signal (b) from a recording and playback head of the automatic telephone answering and recording set through a recording and playback amplifier. Accordingly, there is a chance where the actual remote control signal (a) and the regenerated signal (b) are simultaneously applied to the remote control signal detector. In the both signals, the remote control signal included in the signal (a) is received, but the signal (b) should not be received even if it includes a remote control signal component. To meet with the two requirements, it is customary in the prior art to stop the operation of the remote control signal detector upon detection of the regenerated signal (b) sent to the telephone line, or to temporarily stop the sending of the regenerated signal during application of the remote control signal. However, the former has a defect that no remote control signal can be received during voice detection, and the latter has a defect that the regenerated voice signal being sent out is interrupted.